CVE-2021-37864
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedMattermost 6.1 and earlier fails to sufficiently validate permissions while viewing archived channels, which allows authenticated users to view contents of archived channels even when this is denied by system administrators by directly accessing the APIs.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceMattermost 6.1 and earlier contains an improper authorization vulnerability where the API fails to properly enforce permission checks for archived channel access. Authenticated users can bypass system administrator settings that deny access to archived channel contents by directly calling the API endpoints, allowing unauthorized disclosure of archived messages.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 6.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Mattermost versionAccess the Mattermost system console or check the version through the /api/v4/system endpoint. The version is typically displayed in the system console footer or can be retrieved via API call.Affected if The installed version is 6.1 or any earlier version (e.g., 6.0.x, 5.x.x)
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Verify archived channels existCheck if any channels have been archived in the system. This can be done via the Mattermost UI by viewing the channel list or querying the channels API for channels with the 'archived' status.Affected if There are archived channels in the system that should be protected by access controls
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Confirm admin restriction settings for archived channelsReview the System Console settings under 'Compliance' or 'Advanced' settings to determine if the administrator has enabled restrictions on archived channel access.Affected if Admin has configured settings to restrict or deny access to archived channel contents
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Test API endpoint access to archived channelsUsing an authenticated user account with limited permissions, make direct API calls to endpoints such as /api/v4/channels/{channel_id}/posts for archived channels. Compare the response against expected permission behavior.Affected if The API returns archived channel content without properly enforcing the admin-configured access restrictions
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Check user permissions configurationReview the team's permission scheme in System Console under 'User Management' > 'Permissions'. Verify whether the 'View Archived Channels' permission is properly restricted.Affected if The permission scheme allows authenticated users to access archived channels despite admin-level restrictions being in place
A user is affected if running Mattermost version 6.1 or earlier AND the system contains archived channels with admin-defined access restrictions that are not being enforced by the API.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade Mattermost to version 6.1.1 or later to receive the permission validation fix. Review and test archived channel access controls after applying the update.
Mattermost 6.2 or later
- Upgrade Mattermost to version 6.2 or later to address the improper access control vulnerability in archived channel permissions
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-37864 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-37864 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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